Combination switch control for servo-circuit systems



Jan. 10, 1967 E. v. SCHNEIDER ETAL 3,297,923

COMBINATION SWITCH CONTROL FOR SERVO-CIRCUIT SYSTEMS Filed Sept, 13,1965 2 Sheets-Sheet 1 I i INVENTORS FIG.3C EMMOR v. SCHNEIDER 94 9syANDREW EDEMING aM/fi WM Jan. 10, 1967 51 v. SCHNEIDER ETAL COMBINATIONSWITCH CONTROL FOR SERVO-CIRCUIT SYSTEMS Filed Sept. 13, 1965 2Sheets-Sheet 2 IIIIL TIL I II I I I I I I I I I I I I I I I I INVENTOR5EMMOR V. SCHNEIDER BY ANDREW E DEMING M W M ATTORNEYS United StatesPatent 3,297,923 COMBINATION SWITCH CONTROL FOR SERVO-CIRCUIT SYSTEMSEmmor V. Schneider and Andrew F. Deming, Alliance, Ohio, assignors toConsolidated Electronics Industries Corporation, a corporation ofDelaware Filed Sept. 13, 1963, Ser. No. 308,836 Claims. (Cl. 318-18)This application is a continuation-in-part of our application Serial No.300,838, filed August 8, 1963 and entitled Phase Sensitive Circuit andnow abandoned.

The invention relates in general to antenna rotator devices or otherservo-circuit systems having a motor for turning an antenna or otherelement which may be operated to any one of a plurality of places in arange between first and second rotational limits, and more particularlyto a switching control system for controlling the operation of themotor.

An object of the invention is the provision of a switching controlsystem which avoids the necessity of employing expensive and involvedrelays.

Another object is the provision of a switching control system wherebythe power for energizing the system may be controlled by a single polesingle throw relay and whereby the circuits which establish thedirection of rotation, clockwise or counter-clockwise, in which themotor is to be operated may be controlled by a single pole double throwrelay.

Another object is to provide for establishing circuits to control thedirection of rotation in which the motor is to be operated and forwithholding the energization of the motor until such circuits areestablished.

Another object is the provision of a switching control system whichprovides for making full voltage and power available for pulling in therelays to their correct selective position and which prevents the motorfrom starting until after the selection has been completed.

Another object is the provision of a hold-in relay which when energizedprovides for maintaining energization of the complete system includingthe hold-in relay itself.

Another object is the provision of a switching control system whichprevents needless false starts of the motor in the Wrong direction.

Another object is the provision of a switching control system Where nocombination of relay operation can short the relay contacts across themotor capacitor.

Another object is the provision of a switching control system which iscompletely shut down or de-energized when the motor has completed itstravel as called for by the setting of the control knob.

Another object is the provision of a switching control system in whichthe direction of rotation of the motor, clockwise or counterclockwise,is controlled by a single pole double throw relay, normally biased tomake engagement with one of the two switching contact positions therebynormally causing the motor to operate in one direction, for example,clockwise, whereby, in the event the control knob is set to a newposition calling for the motor to run in said clockwise direction, thesystem prevents or precludes the relay from being operated since therelay is already in the correct position for such clockwise rotation,and whereby, in the event the control knob is set to another newposition calling for the motor to run in an opposite direction,counterclockwise, the system then provides for operating the relay sothat engagement is made with the other of said two switching contactpositions to cause the motor to operate in the counterclockwisedirection, taken in combination with lost-motion switching meanscontrolled by the control knob to pre clude the starting of the motoruntil such relay switching is completed.

Other objects and a fuller understanding of the invention may be had byreferring to the following description and claims, taken in conjunctionwith the accompanying drawings, in which:

FIGURE 1 is a diagrammatic view of a switching control system embodyingthe features of the invention, portions of the servo-circuit systembeing shown in block diagrams;

FIGURE 2 is a diagrammatic view of a switching control system showingall of the electrical circuits of the servo-circuit system;

FIGURE 3 (including 3A, 3B, 3C and 3D) is a graph of voltage and currentconditions explaining the operation of the circuit of FIGURE 2; and

FIGURE 4 is a modified diagrammatic view of the switching controlsystem.

The invention will be described with reference to an antenna rotatordevice but it is understood that the invention may be embodied in anyother servo-circuit system.

With respect to FIGURE 1, the switching control system is arranged tooperate a motor 12 which turns an antenna 36 as called for by thesetting of a control knob 88 having a scale or indicia 89, N., E., S.,W., indicating the direction in which the antenna is to be turned. Thecontrol knob 88 upon being actuated is arranged to start and stop themotor at any one of a plurality of places in a range between first andsecond rotational limits. The system generally comprises a servo-circuitmeans or phase sensitive circuit indicated generally by the blockdiagram 11, a motor circuit means indicated generally by the conductors26 and 27, a hold-in relay 55, a motor switching relay 3.0, and atransformer 13 for energizing the system, the transformer beingenergized from a supply source 19 through feed line conductors 37 and38,, The transformer 13 has a primary winding 18 and a secondary winding22 having end terminals 41 and 42 and a center tap terminal 43 forenergizing the servo-circuit means, and a secondary winding 21 forenergizing the motor circuit means. A lamp 23 may be provided toindicate that the secondary winding 21 is energized.

The servo-circuit means 11 comprises generally, an amplifier circuitmeans indicated by the block 15, first and second directional currentflow devices indicated respectively by blocks 62 and 63, and a bridgecircuit including at least first and second bridge means indicatedrespectively by the blocks 46 and 47. The amplifier circuit means, thedirectional current flow devices, and the bridge circuit of theservo-circuit means are all electrically connected together to performthe required servo-circuit operation, and are shown in block diagrams inorder that attention may be focused on the switch control system. Thehold-in relay 55 is energized through a first circuit, referred tohereinafter as first circuit connection means, which extends from theamplifier circuit means 15 through a conductor 59, the winding of therelay 55 and conductor 60 to the first directional current flow device62. The hold-in relay 55 has a hold-in line contact in the feed lineconductor 37 and upon energization of the relay 55 the holdin linecontact 85 is closed to energize the transformer and the entire system,including the relay 55 itself. The contact 85 when once closed maintainsthe system energized including the relay 55 itself.

The motor switching relay 30 has a movable contact 29 which operatesbetween first and second opposed contacts 31 and 32. The relay 30 isnormally de-energized and under a de-energized condition the movablecontact 29 is making engagement with the first contact 31 thatestablishes a first motor circuit which extends from the secondarywinding 21 through conductor 27, a disabling motor switch 28, contacts'29 and 31, conductor 33, motor winding 24, and conductor 26 back to theopposite terminal of the secondary winding 21. The first motor circuitis adapted to'cause the motor 12 to run in a first direction,

clockwise, for example, towards the first rotational limit. When therelay 30 is energized, themovable contact 29 makes contact with thesecond opposing contact" 32 that establishes a-second motor circuitwhich extends from the secondary winding 21 through the conductor 27,the

disabling motor switch 28, contacts'29 and 32, conductor 34, motorwinding 25, and the conductor 26 'back to the opposite terminal. of thesecondary winding 21. The second motor circuit is adapted to cause themotor 12 to run in a second direction, counter-clockwise, towards thesecond rotational limit. A motor capacitor 35 is connected between thefirst contact 31 and the second contact 32. A relay capacitor 66 isconnected across the winding of the relay 55 and a relay capacitor 67 isconnected across the relay winding 30. The winding of the relay 30 is inseries with the winding of the relay 55 and these two relays jointly areenergized through a second circuit, referred to hereinafter as secondcircuit connection means, which extends from the amplifier circuit means15 through conductor 59, the winding of the relay 55, conductor 64, thewinding of relay 30 and through conductor 65 to the second directionalcurrent flow device 63.

The control knob 88 may be set at any one of a plurality of positions ina range between first and second limit positions and is adapted to havelost-motion means 86 and 87, illustrated as a yoke-86 and a pin 87,therebe tween. The control knob 88 moves the'first bridge means 46through this lost-motion means '86-87. The bridge means 47 is driven bythe motor 12. When the two bridge means are balanced, there is produceda null electrical condition which de-energizes the. relay 55 and, inturn, the entire system. The lost-motion means 86-87'is initiated duringthe first few degrees of rotation and is adapted to temporarily open adisabling motor-contact 28 in the motor circuit and to close a linecontact in the feed line conductor 37. Continued rotationv of the knob88 operates the first bridge means 46 to cause an unbalanced electricalcondition with the bridge means 47 which is driven by the motor 12.Release of the knob 88, after it has been rotated to its desirednewsetting, causes the lost-motion means 86-87 toreclose the disablingmotor contact 28 and reopen the line contact 20.

Thus, in actuating the knob 88 to a particular setting, the disablingmotor contact 28 is temporarily opened and the line contact 20 istemporarily closed, which in actual practice may be one or two seconds,which is much larger than the fractional part of a second required toenergize the relays.

In explaining the operation of the system, let it be assumed that theknob 88 is turned in a first direction (clockwise) calling for the motor12 to turn clockwise. The initial turning of the knob 88 causes thelost-motion means 86-87 to open the disabling motor contact 28 and closethe line contact 20. The tempo ary closure of the line contact 20energizesthe primary winding 18 of the transformer 13 and thetwosecondary windings 22 and 21, which energize respectively theservo-circuit means and the motor circuit means. The energization of thefor preventing the motor from starting until after the selection hasbeen completed, thus preventing needless false starts of the motor inthe wrong direction. In antenna rotator devices, meeting UnderwritersLaboratories requirements, the motor itself is designed to run on 30volts AC. or less'and this islprovided by the transformer which is of astep-down type. The motor load may. be approximately 80 watts and thisreduces the transformer voltage by about 15 percent, which in turnreduces the power developed by the amplifier circuit means 15 by about28 percent as compared to the power which would be developed from thesame circuit without the motor load. Thus, the temporary opening of thedisabling motor contact 28in the motor circuit makes full voltage andpower available-for pulling in the relays.

As previously pointed out, when the knob 88 has been set to its'newclockwise position, the bridge means 46 is caused to be in an electricalunbalanced condition with respect to the motor-driven bridge means 47.Release of the knob 88, after it has once been set at its new clockwiseposition, causes the lost-motion means 86-87 to reclose the disablingcontact 28 and reopen the line contact 20. The opening of the linecontact 20 does not affect the operation of the system, because by nowthe hold-in parallel contact 85 has been closed. The closure of thedisabling motor contact 28 energizes the motor I circuit. The unbalancedelectrical condition caused by turning the bridge means 46 creates afirst phase condition whereby the relay 55 is energized through thefirst circuit connection means extending from the amplifier means 15,the conductor 60, to the directional current 30 is precluded from beingoperated under this first phase servo-circuit means energizes the relay55 which closes the hold-in contact 85 for maintaining the systemenergized. The opening of the disabling motor contact 28 condition, itremains de-energized, leaving the movable arm 29 where it was, that is,normally biased against the contact 31, which aligns the motor to run ina clockwise direction. In other words, the relay 30 was already in itscorrect position for causing the motor to run in a clock-' at a placecalled for by the new-clockwise setting of the control knob 88 upon thede-energization of the complete system. I

Now let it be assumed that the knob 88 is turned in a second direction,counter-clockwise, to another new selection position calling for themotor to run counter-.

clockwise. In turning the knob 88 counter-clockwise, the lost-motionmeans 86-87 opens the disabling motor contact 28 and closes thelinecontact 20, the knob performing the same operation as it did when itwas turned clockwise. The closing of the line contact 20 energizes thecomplete system and the opening of the disabling motor contact 28de-energizes the motor, the same as previously explainedwhen the knobwas turned clockwise. However, the turning of the knob in acounter-clockwise direction actuates the bridge means 46 in a reversedirection and this establishes a reverse unbalanced electrical conditionwith the motor-driven bridge means 47, creating a second phase conditionjust the reverse from the first phase condition which was created whenthe knob was turned in a clockwise direction. Under this second reversedphase condition, both the relays 55 and were energized through thesecond circuit connection means extending from the amplifier means 15,the conductor 59, the winding of relay 55, conductor 64, the winding ofrelay 30 and through conductor 65 to the second directional current flowdevice 63. Under the second reversed phase condition, the directionalcurrent flow device 62 is open circuited and thus the relay 55 isprecluded from being energized through this directional current flowdevice 62 as it was before when the knob was turned in a clockwisedirection. Energization of the hold-in relay 55 closes the hold-in linecontact 85 which energizes the entire system as explained before.However, ener-gization of the motor switching relay 30 causes themovable contact 29 to swing to its opposite position and make engagementwith contact 32, aligning the motor to run in a counter-clockwisedirection, as called for by the setting of the knob in acounter-clockwise position. Counterclockwise operation of the motorcauses the bridge means 47 to be moved to a balanced condition with thebridge 46. The rebal-ancing of the two bridge means 46 and 47establishes a null electrical condition which causes the amplifier 15 todecrease its conduction, thus de-energizing the relay 55, whereupon theentire system is de-energized upon the opening of the hold-in linecontact 85. The motor 12 is thus stopped at a place called for by thenew counter-clockwise setting of the control knob 88 upon thede-energization of the complete system.

The capacitor 67 across the relay 3% is of a larger capacity than thatof capacitor 66 across the relay '55. The capacitor 67 having a longertime constant, assures that the relay 55 will be the first to pull inand the first to drop out. Thus, it is the opening of the line contact85 that de-energizes the motor circuit along with the entire system andnot the contacts of the relay 30. This assures that the entire circuitwill be de-energized before the movable contact 29 of the relay 30 ischanged back to make its normal engagement with the contact 31 uponde-energization thereof. Thus, there will not be any last minutereversal of the motor just as the complete system is de-energized.

In this invention, single pole relays are used with a cost saving, andno combination of relay operation can short the contacts arross themotor capacitor. The system is completely shut down when the end ofmotor travel is reached as called for by the setting of the knob. Agreat saving in the life of the relay 30 is effected because it is onlyoperated on half the starts, namely, in counter-clockwise direction, butbecause of the disabling motor switch 28, no false direction isinitiated. Regardless of direction of unbalance of bridge means, therelay 55 is closed.

The servo-circuit means 11 may be of any suitable design. The amplifiermeans may employ tubes, transistors, or any other amplifier devices. Thedirectional current flow devices 62 and 63 may comprise diodes, or anyother such devices. The bridge means 46 and 47 may comprise suitablepotentiometers, or like devices.

The circuit of FIGURE 2 shows a preferred embodiment of a switchingcontrol system showing all the electrical circuits for the servo-circuitmeans, applied for purpose of explanation only, to an antenna rotator.The electrical parts or elements of FIGURE 2 which correspond to likeparts in FIGURE 1 are identified by the same reference characters.FIGURE 2 shows a servocircuit or phase sensitive circuit 11 used tocontrol the motor 12. The circuit of FIGURE 2 includes, generally, thetransformer 13 energizing the motor 12 and additionally a bridge circuit14 and an amplifier circuit 15. As in FIGURE 1, the transformer 13 has aprimary 18 energized from an alternating voltage source 19 through feedor line conductors 37 and 38 controlled'by the line contacts 20. Thetransformer has first and second secondaries 21 and 22 with the firstsecondary 21 energizing the pilot lamp 23 and connected to energizemotor windings 24 and 25. A conductor 26 extends from the secondary 21to a common terminal of the motor windings 24 and 25 and a conductor 27extends from the other end of the secondary 21 through the normallyclosed contacts 28 and through the single pole double throw contacts 29of relay 30 selectively through contacts 31 and 32 and throughconductors 33 and 34 selectively to the motor windings 24 and 25. Acapacitor 35 is connected across the conductors 33 and 34 to provide aleading or lagging phase current to the motor winding 25 relative tomotor winding 24. By this means the rotor of the induction motor 12 maybe rotated selectively in either direction to rotate an antenna 36 asrepresentative of a load.

The bridge circuit 14 is energized from end terminals 41 and 42 of thetransformer secondary 22, which secondary also has a mid tap 43. Thebridge circuit 14 also includes a first impedance 4-4 and an outputterminal 45 and first and second potentiometers 46 and 47 connected inseries across the end terminals 41 and 42. Thus, the first impedance 44is a first leg of the alternating current bridge 14 and the first andsecond potentiometers 46 and 47 connected in series by conductors 48 and49 constitute the second leg of this bridge. The two halves of thesecondary 22 may be considered as the voltage source for the bridge plusthe third and fourth legs of this bridge as Well. The mid tap 43 is,thus, the second output terminal of this bridge. All five conductors,2'6, 33, 34, 48 and 49 may pass through a terminal strip 50 and thus itwill be seen that the antenna rotator or load motor 12 may be remotelyconnected to the phase sensitive or servo-circuit 11 by a five-conductorcable.

The output terminals 43 and 45 supply a phase sensitive input signal toa common amplifier, in this case shown as a transistor 54, as a part ofthe amplifier circuit 15. The motor 12 is a load responsive to twodifferent phase conditions and is controlled through the relay 30 and arelay 55'.

The transistor 54 has a base 53, an emitter 56 and collector 57. Theemitter 56 is connected by a conductor 58 to the mid tap 43. Thecollector 57 is connected by a conductor 59 through the coil of therelay 55, a conductor 60, a voltage dropping resistor 61 and through afirst directional current flow device or diode 62 to the first endterminal 41. The collector 57 is also connected through the conductor59, the coils of relays 55 and 30 in series by means of a conductor 64and a conductor 65 through a second directional current flow device ordiode 63 to the end terminal 42. Filter capacitors 6'6 and 67 areconnected across the coils of relays 55 and 30, respectively.

The first and second diodes 62 and 63 supply a DC. voltage by means offilter resistors 68 and 69 connected in series across the anodes of thediodes 62 and 63. The junction 70 between the resistors 68 and 69 isconnected through a filter capacitor 71 to the mid tap 4 3. The polarityof the diodes 62 and 63 makes the junction terminal 70 negative relativeto the mid tap 43. The base 53 of the transistor 54 is connected througha coupling capacitor 72 and a resistor 73 to the terminal 70.

A transistor pre-amplifier 76 may be provided in the amplifier circuit15 for added sensitivity. Although such pro-amplifier may be omittedWhere coarse control is sufficient or where an impedance matchingtransformer is used. The bridge output terminal 45 is connected througha current limiting resistor 77 to the base 78 of the transistor 76 andthe emitter 79 of the transistor 76 is connected to the mid tap 43,which is the other output terminal of the bridg Accordingly, the bridgeoutput is applied to the input electrodes of the transistor 76. Thecollector 80 of the transistor 76 is connected to a terminal '81 at thejunction of capacitor 72 and resistor 73. Accordingly, the outputcircuit of the transistor 76 may be traced from the positive directcurrent source terminal 43 through the emitter 79, the collector '80 andthe resistor 73 to return to the direct current source negative terminal70. Accordingly, resistor 73' is the load .resistor of the pre-amplifiertransistor 76 and is the source of input signals supplied through thecoupling capacitor 72 to the main transistor amplifier 54.

The relay 55 actuates hold-in line contact 85 which is normallyopen andwhich is in parallel with the line switch contact 20, to, maintain thetransformer 13.energized after energization of the relay 55. The firstpotentiometer 46 maybe the control potentiometer and is one example of avariable impedance which controls the phase of the input signals. Themovable blade. of this first potentiometer 46 is moved through alost-motion means depicted as .a yoke 86 anda pin '87 therebetween.Amanual control knob 88 moves the potentiometer 46 through thislost-motion means 8 6457. The knob 88 may cooperate with a scale orother indicia. 89 to indicate the desired rotational direction of themotor-driven antenna 36. The lost-motion means 86-87 may take one ofmany forms. For example, itmay be the same as shown in the co-pendingapplication Serial No. 100,152 entitled Remote Control Device, filedApril 3, 1961, now Patent No. 3,126,506, issued March 24, 1964. Movementof the knob "88 first takes up the lost motion and then rnoves themovable blade of the potentiometer 46. As the lost-motion means 8687 isactuated, the switch contacts 20 and 28 are actuated. This movementopens the disabling motor switch contact 28 and closes line contact 20,and release of the knob 88 performs the opposite function, namely, toclose the disabling motor contact 28 and open the line contact 20. Themotor 12 is connected to drive the second potentiometer. .for afollow-up or closed loop servomotor system. Y

The circuit of FIGURE 2 may be operated by grasping the manual knob 88and moving it to a new selected position, for the antenna 36. Thepotentiometer 47 may be the type which will permit a full 360-delgreerotation and alternatively, the potentiometer 47 may be of the ordinarytype of about SOD-degree rotation between stops of the potentiometer 47.Assume that the antenna is oriented towardthe east and the knob 88 isgrasped and rotated clockwise, as per'arrow 96, to the south position.This movement of the knob 88 opens the. disabling motor switch contact28 and closes the line switch contact 20 by means of the lost-motionconnection 8687 before the potentiometer46 is moved. This lost 'rmo-tionmay be only one to three degrees, for example, just suflicient toactuate the switches 20 and 28. The closing of the first line switchcontact20 energizes the primary 1 8 and the entire transformer 13. Theopening of the'disabling motor switch contacts 28- prevents enengizationof the motor 1 2-at this time. The energization of the transformer secondary 2 2 energizes both the bridge circuit 14 and the amplifiercircuit 15. The clockwise movement of potentiometer 46 decreases theresistance thereof and hence decreases the impedance in this second legof the bridge which includes potentiometers 46 and 47. Accordingly, thealternating current bridge 14 will have an output voltage at terminals43 and 45. This output voltage will either be in phase with the voltagefrom mid tap 43 to terminal 42. In this case, with the decreasingresistance of potentiometer 46, the potential of terminal 45 will shiftin phase to the right, and hence the voltage from mid tap 43 to terminal45 will be in phase with the source voltage from mid tap 43, to endterminal 42. FIGURE 3A illustrates the voltage curve91 of the voltage ofterminal 41 relative to terminal 42, as a reference. Thus, when terminal41 goes positive, the output terminal 45 will go negative because thisoutput signal is directly out of phase with the voltage from terminals42 and 41. This condition is illustrated in the.left half of FIGURES 3A-3D and the output signal 92 of the bridge is illustrated in FIGURE 3B.This is shown as being out of phase with thereference'voltage-91,whichz-is the voltage from terminal 42 to, terminal41. Thus, in the first half cycle, when terminal 41 is positive terminal45 goes negative. This applies a negative bias to the base 78 oftransistor 76 causing this transistor to increase conduction through theload resistor 73. This transistor current is shown in FIGURE 3C as curve93. The terminal 81 thus becomes v ducting state.

8 increasingly positive on this half cycle and, hence, the transistor 54is biased into complete non-conduction.

A bias resistor 82 is connected between the base 78 of transistor 76 andterminal 70. This provides a small leakage current so that transistor 76is biased into a partially conducting region. A self bias resistor 83 isconnected between the base 5-3 and emitter 56 of, transistor 54, withtransistor 54 normally biased in a substantially non-con- Thistransistor 54 is normally biased by resistor 83 as a self bias resistor,and hence, the normal condition of this transistor 54 is substantially anon-conducting condition. During the next half cycle of the referencevoltage 91, however, the bridge output voltage at terminal 45 is goingpositive and this decreases the conduction of transistor 76 to make theterminal 81 less positive or more negative. This more negative voltageswing is applied through the coupling capacitor 72 to the base '53 oftransistor 54, hence biasing it into a conducting state. The currentthrough the main transistor 54 is shown as curve 94- in FIGURE 3D.Accordingly, a half wave pulse of current 94 is passed by the transistor54 in the second half cycle of the reference voltage 91. This half wavepulse of current passes through the first circuit connection meansincluding collector 57 and through the coil of relay 55, the voltagedropping resistor 61 and diode 62 to the terminal 41 which is'at thattime negative. Current cannot flow through the second circuit connectionmeans from the collector 57 through the two relay coils 55 and 30 inseries to the terminal 42 because it is atthat time positive and thepath is open circuited by diode 63. The capacitor 66 across the coil ofthe relay 55 smoothes these half wave pulses to maintain this relay 55energized. The hold-in line contact 85 of this relay 55 is thus closedtomaintain energized the transformer r13. At this time the knob 88 may bereleased and this will open the line contact 20 but this has no effecton the circuit since in the practical case, the relay 55 will beenergized in less than second after movement of po tentiometer 46 tounbalance the bridge circuit 14.

The relay 30 has not as yet been energized, hence the closing of thedisabling motor contact 28 establishes a motor energization circuitdirectly to motor winding 24 with leading current supplied throughcapacitor 35 to the motor winding 25. Accordingly, the motor 12 will runin a clockwise direction to rotate the antenna 36 to the desired southorientation. Also the potentiometer 47 is rotated clockwise to increasethe resistance thereof and upon rebalance of the bridge circuit14, theoutput voltage of the bridge fallsto a null and thus the relay 55 willbecome de-energiz'ed to open the hold-in line'contact 85 and de-energizethe complete circuit 11. This will be where the antenna '36 has beenpositioned to" the desired orientation as established by movement of thepoitentiometer 46 in this clockwise direction.

Now assume that the potentiometer 46 is moved counter-clockwise, asshown by arrow 97 in FIGURE 2 and by the right half of FIGURE 3. Thiscounter-clockwise movement increases the resistance of potentiometer146,

:This shifts the phase of the terminal point 45to the left,

that is, the bridge output voltage from terminals 43 to 45 is in phasewith the voltage from terminals 43 to 41 of the reference voltage 91.FIGURE 3B shows this voltage curve 92 now as being in phase with thereference volt- "age'91of FIGURE 3A. AS the potential of terminal 41 .93in the right half of FIGURE 3C. This decreasing cur-' rent throughtransistor 76 decreases the current through.

the load resistor 73 and hence the potential of terminal 81 is lesspositive or more negative. This more negative swinging voltage isapplied through coupling capacitor 72 to the base 53 of transistor 54 tothus cause conduction of this transistor 54. This is shown by the pulseof current 95 in FIGURE 3D. This current pulse is in the first halfcycle of .the reference voltage. This pulse of current is passed throughthe transistor 54 and goes through the second circuit connection meansfrom collector 57 through the two relay coils 55 and 30' in series andthrough the diode 63 to the terminal 42 which is negative in that halfcycle. The capacitors 66 and 67 smooth this half cycle pulse of currentto cause continuous energization of the relays 30 and 55.

As before, the energization of relay 55 closes its contact hold-in line85 to maintain the entire circuit 11 energized. The energization ofrelay 30 moves the contact arm 29 to energize the contact 32 and thisenergizes the motor winding 25 directly and the motor winding 24 with aleading current through the capacitor 35. This is another way of sayingthat in this energization condition, the motor winding 25 has a laggingcurrent relative to that current through motor winding 24. This is thereverse energization condition to that established with clockwiserotation of potentiometer 46, and accordingly, the motor 12 will rotatecounter-clockwise to drive the antenna to its newly selected position.This also drives the potentiometer 47 in a counter-clockwise directionto rebalance the bridge by decreasing the resistance. Again, uponrebalance of the bridge, the null condition will be achieved at thebridge output terminals 43 and 45 which will cause cessation of currentconduction through transistor 54 and de-energization of the relays 55-and 30. De-energization of relay 55 de-energizes the entire circuit andtie-energization of relay 30 permits its return to its normal conditionengaging contact 31. Capacitor 67 may be made of a larger capacity thancapacitor 66. This will achieve a longer time constant and will assurethat the relay 55 will be the first to pull in and the first to dropout. Since relay 30 will be the last to drop out, this means the hold-inline contact 85 of relay 55 is the switch which actually interrupts thecurrent and relay contacts 31 and 32 will not interrupt the current;hence, this may be made a light duty relay for economy. Also, thisassures that the entire circuit will be de-energized before relay 30changes its contact condition. Thus, there will not be any last minutereversal of the motor 12 just'as the circuit is de-energized.

Additionally, the disabling motor switch 28 perfiorms a desirablefunction of preventing energization of the motor 12 until the motordirection of rotation has been established. Both the relays 55 and 30will be energized within about second after movement of thepotentiometer 46 in a counterclockwise direction. Alternatively, if thepotentiometer 46 is rotated clockwise, only relay 55 is energized, asset forth above. Either of these two energization conditions occurswithin the aforesaid second and, hence, the motor direction of rotationis established within this short period of time after movement of thepotentiometer 46. Accordingly, after the knob 88 is moved to the desirednew position for the antenna 36, this knob 88 may be released at anytime after this second and the motor direction of rotation will alreadyhave been established. This prevents the motor from starting rotation inone direction and then changing direction immediately thereafter shouldthe relay 30 pull in after the motor started rotating in the oppositedirection. Thus, this disabling motor switch 28 provides this desirablefunction of preventing false initial direction of rotation of the motor12.

Accordingly, the above description shows that the input may have twodifferent phase conditions. With the first phase condition of the input,only relay 55 is energized and with the second phase condition of theinput,

both relays 30 and 55 are energized. Both of these phase conditions areamplified by the common amplifier 54 but separate circuit paths areprovided from this transistor 54 to the voltage source of the secondary22. One such circuit path is through relay 55 alone and diode 62 and theother circuit path is through the two relays 55 and 30 in series and thediode 63. These two different relay energization conditions establishtwo different directions of rotation of the motor 12. Accordingly, itwill be seen that the transistor 54 is connected in two separate pathsof difierent phase responsive character so that phase reversal of theinput from the bridge 14 causes phase selective current flow in the twoseparate circuit paths. Further, it will be seen that when the inputsignal to the amplifier is of one phase characteristics, the motor willoperate in one direction and when the input signal is of another phasecharacteristic, the motor 12 will operate in the other direction, bothas established by the two separate circuit paths from the commonamplifier 54.

FIGURE 4 shows a modified phase sensitive or servocircuit 151 quitesimilar to that shown in FIGURE 2. This circuit 151 incorporates anamplifier circuit 155 again similar to that shown in FIGURE 2, exceptfor changes in the relay circuit which is the load for the mainamplifier 54. This amplifier circuit 155 supplies energy to two relays,161 and 162. The relay 162 is similar to the relay 55 of FIGURE 1 tocontrol contacts for the pri mary energization circuit, since this relay162 is always energized whenever the bridge output voltage is beingconducted through transistor 54. Relay 161 is similar to the relay 30 inFIGURE 1 to selectively control energization to the motor windings 24and 25 for selected direction of rotation. In such a modified circuit,the relay 161 is connected from the collector 57 of transistor 54through a conductor 164 to coil of relay 161, and conductor 165 throughdiode 62 to the voltage source terminal 41. Capacitor 66 is connectedacross the coil of relay 161 to maintain this relay closed even thoughenergized with half-wave pulses. The coil of relay 162 is connected fromthe collector 57 of transistor 54 by means of conductors 164 and 169,and a conductor to the negative direct current voltage source terminal70. In this circuit of FIGURE 4, relay 161 controls a double throwcontact 171 and constitutes a reversing switch for the motor 12. Therelay 162 controls a single throw contact 172.

Conductor 27 leading from the secondary 21 leads to the contact 171 andthe opposed contacts are connected respectively to the motor windings 24and 25 through conductors 33 and 34. The contact 171 is normally biasedto energize motor winding 25 when the relay 161 is de-energized. Therelay contact 172 is connected in the energization line from thealternating current voltage source 19 to the primary 18 and is connectedin parallel with the manual switch contacts 20. The amplifier circuit155 is shown as having a slightly different direct current voltagecircuit from that shown in FIGURE 2. A diode 175 replaces the resistor68 and resistor 69 is eliminated. This shows that the direct currentvoltage source developed across the filter capacitor 71 may be obtainedby a half-wave rectifier rather than a full-wave rectifier. Also, thediode 175 in replacing the resistorv 68, provides an additional functionof preventing leakage current which might otherwise flow throughtransistor 54. If the resistor 68 of FIGURE 2 were retained in FIGURE 4,leakage current could flow through transistor 54, through relay coil161, through resistor .68, through the direct current voltage source andreturn to the emitter of transistor 54. If the transistor 54 leakedenough current during its normally non-conducting periods, this mightpossibly cause energization of relay 161 at undesired phase portions ofthe reference voltage. Use of this diode 175 prevents such occurrence.

The circuit of FIGURE 4 operates in a manner similar to that for FIGURE2. It will be noted that the two relays 161 and 162 operate on differentphase characteristics of the input. Relay 162 actually operates fromdirect current and relay 161 operates on half-wave pulses supplied whenterminal 41 is negative and when the input signal is in phase with thesecond half cycle of the reference voltage. Thus, it will be seen thatthere are two separate circuit paths from the transistor 54 to voltagesource means with difierent phase responsive characteristics sothatphase reversal of the input causes phase selective current flow in saidseparate circuit paths. If the manual knob 88 is moved clockwise, thisopens switch 28 and also moves the potentiometer clockwise in thedirection of the arrow 6. This decreases the resistance and shifts thephase of the point 45 to be in phase with the voltage from terminal 43to terminal 42. Again, this will cause conduction through the transistor54 on a second half cycle relative to the reference voltage, such asis'shown' in the left half of FIGURE 3A-3D. This conduction willenergize the relay 161 because the terminal'41 is negative during thathalf cycle. This energization of therelay 161 reverses the contacts 171thereof for direct energization of the motor winding 24 and leadingcurrent -energization through capacitor 35 of the motor winding 25. Thiscauses clockwise rotation of the motor 12 and rotation of the antenna 36toward the desired position; Also, the mdtor 12 drives the potentiometer47 toward rebalance of the bridge.

The turn-on of the transistor 54 also energizes the relay 162 sinceitissupplied wtih a direct current operational' voltage from thedirectcurrent voltage source developed across the "filter capacitor 71.Energization of relay 162 closes the contacts 172 thereof and, hence,maintains energized the primary circuit of the transformer 13.Accordingly, the knob 88 may be released to close switch 28 and openmanualswitclt 20 and again this energization of the relay 162 will takeplace within about second.

Upon rebalance of the bridge, the voltage output of the bridge will fallto a null to cause the transistor 54 to cease conduction, and, thus,deenergize the relays 161 and 162. This, of course,de -energizes theentire circuit by opening the relay contacts 172.

I If the knob 88 is moved in a counter-clockwise direc- The operation ofFIGURES 2' and 4has been described as stating that Where thepotentiometer 46 is rotated clockwise, for 'example,-then the motor 12also rotates clockwise. 'If the potentiometer 46 is of the type whichdirection across the point where this potentiometer changes from maximumto minimum impedance and then the motor will rotate in the appropriatedirection, which may be the opposite direction in order to effect arebalance of the bridge circuit. For example, suppose that thepotentiometer had the change from maximum to tion, this moves the manualpotentiometer 46 in a counterclockwise direction as shown by the arrow97. This establishes the set of conditions shown inthe. right half ofFIGURE 3A to 3D. The phase of the bridge output voltage will then be inphase with the source voltage from terminals 43 to 41. This preventsenergization of-relay 161, because blocked by diode 62. Thisestablishes. a

circuit for direct energization of motor winding 25 through relaycontacts 171.

Themotor runs counter-clockwise to move the antenna to the desiredposition and the potentiometer .47 is also driven counter-clockwise todecrease the resistance v.there-.

of toward a rebalance of the bridge. Again, upon bridge rebalance, thetransistor 54 ceases conduction .to deenergize relays 162 and 163 tode-energize the entire circuit.

The circuits of FIGURES 2 and 4 are shown as'motor control circuits butit will be observed that they are control systems or apparatus forsensing the phase and, more particularly, a reversal of phase of analternating current input voltage. The first and second diodes 62 and 63together with the alternating current source of the secondary 22.formfirst and second power supply means of differingphase responsivecharacter and wherein the two power supply means are each conductiveonly on opposite half cycles of the voltage of the alternating currentsource. V

The transistor 54 is a form of amplifier having input and output meansand more particularly is shown as a semi-conductor amplifier havingfirst, second and third electrodes. This is broadly a type of amplifierin all three circuits which is capable of amplifying two input signalsof difiering phase responsive character with first and second load meansin the output of the amplifier in separate circuit paths.

Con-currently with the. turn-on .of, the transistor 54, the relay 162 isagain energized to close the contacts 172 and maintain the entirecircuit energized.

minimum impedance at the South position and no physical stops wereprovided, then if one rotated the knob clockwise from the SE. to the SW.position through a -degree arc, then this would first decrease and thenincrease the impedance which would give a signal, upon release of knob88, so that the motor would rotate in the opposite direction, namely,counter-clockwise, to drive the potentiometer 47 counter-clockwise todecrease the impedance thereof toward a rebalance of the bridge.Accordingly, it will be noted that all the circuits are follow-up motorcontrol systems which tend to establish a rebalance of the bridgeregardless of the direction of upsetting influence in the bridgecircuit.

The present disclosure includes that contained in the appended claims,as Well as that of the foregoing .de-

scription.

Although this invention has been described in its pre ferred form with acertain degree of particularity, it is understood that the presentdisclosure of the preferred form has been made only by way of exampleand that numerous changes in the details of the circuit and thecombination and arrangement of circuit elements may be resorted towithout departing from the spirit and scope of the invention ashereinafter claimed. I

What is claimed is:

1. In an antenna rotator device having a motor to rotate an antennatoany one of a plurality of places, the

improvement of a switching control system comprising, actuating controlmeans operable to be set at any one of a plurality of positions, meansto energize said motor,

relay switching means having first alignment contact; means normallyclosed to align said motor energizing means in a first condition forrotating said motor in a first direction and having second alignmentcontact means normally open and disposed to align said motorlenergizQresponsive to movement of said actuating control means in said seconddirection to provide interruption of said normally closed firstalignment contact means and closure zaof said normally open secondalignment contact means and thereby change said motor energizing meansfrom 7 said first condition to said second condition, disabling motorswitch means having disabling contact means normally closed in serieswith said relay switching means, and means controlled by said actuatingcontrol means to momentarily open said disabling contact means of saidmotor switch means and thereby momentarily withhold energization of saidmotor to prevent a false motor start.

' 2. A device as claimed in claim 1 wherein said actuating control meansincludes lost motion means,

and said means controlled by said actuating control means is controlledby said lost motion means. 3. A'device as claimed in claim 1 whereinsaid actuating control means includes. lost motion means,

said means controlled by, said actuating control means is controlled bysaid lost motion means upon initial actuation of said actuating controlmeans to momentarily open said disabling contact means and therebywithhold energization of said motor until after at least one of saidfirst and second conditions of said motor energizing means isestablished by said alignment contact means,

and means controlled by said lost motion means upon release of saidactuating control means to close said disabling contact means toenergize said motor.

4. Switch control system for starting and stopping a motor driven loadat any one of a plurality of places, said system comprising, actuatingcontrol means operable to be set at any one of a plurality of positions,means to energize said motor, bridge circuit means, transformer means toenergize said motor circuit means and said bridge circuit means, relayswitching means having first alignment contact means normally closed toalign said motor energizing means in a first condition for rotating saidmotor in a first direction and having second alignment contact meansnormally open and disposed to align said motor energizing meansin asecond condition for rotating said motor in a second direction, saidbridge circuit means being actuated by said actuating control means andby said motor, movement of said actuating control means in a firstdirection precluding operation of said relay switching means wherebysaid first alignment contact means remain normally closed to maintainsaid motor energizing means in said first condition and reverse movementof said actuating control means caus ing operation of said relayswitching means whereby said normally closed first alignment contactmeans is interrupted and said normally open second alignment contactmeans is closed to change said motor energizing circuit from said firstcondition to said second condition, hold-in relay means energized fromsaid bridge circuit means and having hold-in contact means normally openwhen deenergized, and line switch means responsive to initial movementof said actuating control means in either direction to energize saidtransformer means which in turn energizes said hold-in relay means tomaintain said transformer means energized independent of said lineswitch means.

5. A system as claimed in claim 4 wherein said rebalancing of saidbridge circuit means establishes deenergization of said system,

and said hold-in relay means having means to cause it to dee'nergizequicker than said relay switching means to prevent last minute reversalof said motor as said entire system is being deenergized.

6. A system as claimed in claim 4, including disabling motor switchmeans having disabling contact means normally closed in series with saidalignment contact means of said relay switching means, said disablingmotor switch means being responsive to initial movement of saidactuating control means in either direction to open said disablingcontact means, and release of said actuating control means aftermovement in either of said directions closing said disabling contactmeans and energizing said motor, whereby said motor continues to operateuntil said bridge circuit means is actuated by said motor to establish abalanced condition thereby producing a null electrical condition forde-energizing said hold-in relay means resulting in the deenergizationof the entire system and the stopping of said motor.

7. A servo-circuit system having a motor to rotate an element to any oneof a plurality of places in a range between first and second rotationallimits, the improvement of a switching control system comprising,actuating control means operable to be set at any one of a plurality ofpositions in a range between first and second limit positions, motorcircuit means, relay switching means having first alignment contactmeans normally closed to establish a first motor circuit for rotatingsaid motor in a first direction toward said first rotational limit andhaving second alignment contact means normally open and disposed toestablish a second motor circuit for rotating said motor in a seconddirection toward said second rotational limit, first means responsive tomovement of said actuating control means in said first direction towardssaid first limit position to establish a first electrical phasecondition to preclude operation of said relay switching means andthereby prevent interruption of said normally closed alignment contactmeans, second means responsive to movement of said actuating controlmeans in said second direction toward said second limit position toestablish a second electrical phase condition for operating said relayswitching means and thereby cause interruption of said normally closedfirst alignment contact means and closure of said normally open secondalignment contact means, disabling motor switch means normally closed inseries with said alignment contact means, and means to momentarily opensaid disabling motor switch means and thereby momentarily withholdenergization of said motor until after at least one of said first andsecond motor circuits is established.

8. A motor control circuit for operation from an alternating voltagesource comprising in combination, first and second relay means, saidsecond relay means having contact means connected to energize said motorcontrol circuit from the voltage source, said first relay means havingdouble throw contact means connected to control the bi-directionalrotation of said motor, actuating control means having first and secondconditions, means controlled by said first condition of said actuatingcontrol means to energize only said second relay means for energizationof said motor control circuit for rotation of said motor in a firstdirection, means controlled by said second condition of said actuatingcontrol means to energize both said first and second relay means toenergize said motor control circuit for motor rotation in the oppositedirection, disabling switch means normally closed in series with saiddouble throw contact means of said first relay, and means controlled bysaid actuating control means to momentarily open said disabling switchmeans and thereby momentarily withhold energization of said motorcontrol circuit.

9. In a motor control circuit to move a load in first and seconddirections, the improvement of a switching control system comprising,actuating control means operable to be moved in first and seconddirections, first relay means having first contact means normally closedto establish motor rotation for movement of said load in said firstdirection and having second contact means normally open to establishupon closing thereof motor rotation for movement of said load in saidsecond direction, first means responsive to movement of said actuatingcontrol means in said first direction to preclude interruption of saidnormally closed first contact means and thereby maintain the directionof load movement in said first direction, second means responsive tomovement of said actuating control means in said second direction toprovide interruption of said normally closed first contact means andclosure of said normally open second contact means and thereby changethe direction of load movement to said second direction, second relaymeans, means to energize said second relay means in response to saidfirst means and to said second means, contacts actuated by said secondrelay means to energize said motor control circuit and start switchmeans in parallel with said contact means of said second relay means toenergize said motor control circuit.

10. A switching circuit for operation of an electrical load from analternating voltage source comprising in combination, first relay meanshaving double throw contact means connected to select first and secondalternative energization conditions of said electrical load, secondrelay means having contact means connected to energize said switchingcircuit from said voltage source, actuating control means operable to bemoved in first and second directions, means controlled by said firstcondition of said l5 a actuating control means to energize only saidsecond relay means for energization .of said switching circuit forenergization of said load in said first energization condition, meanscontrolled by said second condition of said actuating control means toenergize both said first and second relay means to energize saidswitching circuit for energization of said load in said secondenergization condition, disabling switch means normally closed in,series with said load and said double throw contact means, and meanscontrolled by said actuating control means to momentarily open saiddisabling switch means and thereby momentarily withhold energization ofsaid load.

References Cited by the Examiner UNITED STATES PATENTS 1 2,637,831"5/1953 Eachus 318289 X 2,863,107 1/1956 Blauvelt 318-207X 3,068,3 812/1962 'Burski 318-29 3,126,506 3/1964 Schneider 318-207 3,155,88911/1964 Stiles et a1. 318- 29 ORIS L. RADER, Primary Examiner. JOHN FLCOUCH, Examiner.

B. DOBECK', Assistant Examiner.

1. IN AN ANTENNA ROTATOR DEVICE HAVING A MOTOR TO ROTATE AN ANTENNA TOANY ONE OF A PLURALITY OF PLACES, THE IMPROVEMENT OF A SWITCHING CONTROLSYSTEM COMPRISING, ACTUATING CONTROL MEANS OPERABLE TO BE SET AT ANY ONEOF A PLURALITY OF POSITIONS, MEANS TO ENERGIZE SAID MOTOR, RELAYSWITCHING MEANS HAVING FIRST ALIGNMENT CONTACT MEANS NORMALLY CLOSED TOALIGN SAID MOTOR ENERGIZING MEANS IN A FIRST CONDITION FOR ROTATING SAIDMOTOR IN A FIRST DIRECTION AND HAVING SECOND ALIGNMENT CONTACT MEANSNORMALLY OPEN AND DISPOSED TO ALIGN SAID MOTOR ENERGIZING MEANS IN ASECOND CONDITION FOR ROTATING SAID MOTOR IN A SECOND DIRECTION, FIRSTMEANS RESPONSIVE TO MOVEMENT OF SAID ACTUATING CONTROL MEANS IN SAIDFIRST DIRECTION TO PRECLUDE INTERRUPTION OF SAID NORMALLY CLOSED FIRSTALIGNMENT CONTACT MEANS AND THEREBY MAINTAIN SAID MOTOR ENERGIZING MEANSIN SAID FIRST CONDITION, SECOND MEANS RESPONSIVE TO MOVEMENT OF SAIDACTUATING CONTROL MEANS IN SAID SECOND DIRECTION TO PROVIDE INTERRUPTIONOF SAID NORMALLY CLOSED FIRST ALIGNMENT CONTACT MEANS AND CLOSURE OFSAID NORMALLY OPEN SECOND ALIGNMENT CONTACT MEANS AND THEREBY CHANGESAID MOTOR ENERGIZING MEANS FROM SAID FIRST CONDITION TO SAID SECONDCONDITION, DISABLING MOTOR SWITCH MEANS HAVING DISABLING CONTACT MEANSNORMALLY CLOSED IN SERIES WITH SAID RELAY SWITCHING MEANS, AND MEANSCONTROLLED BY SAID ACTUATING CONTROL MEANS TO MOMENTARILY OPEN SAIDDISABLING CONTACT MEANS OF SAID MOTOR SWITCH MEANS AND THEREBYMOMENTARILY WITHHOLD ENERGIZATION OF SAID MOTOR TO PREVENT A FALSE MOTORSTART.